there was a significant increase in the number
of immediate early and early gene transcripts
in ISS astronaut samples as compared to
healthy control samples and shuttle
astronauts at landing. A related study focused
on “monocytes,” a type of white blood cell,
which play multiple roles within the immune
system. Evidently, the more complex and
greater the workload and associated stress
crew members experienced, the more their
immune function (in this case monocyte
parameters) appeared to be compromised,
mainly in the reduction of the body’s defense
signaling capability and pronounced
suppression of the immune system’s ability to
identify and neutralize potential pathogens.
Researchers also found increases in the stress
hormone cortisol in shuttle crew members, presumably due to the rigors of preflight training,
which were accompanied by significant changes in white blood cells even days prior to launch.
It is important to note, however, that for short-duration crew members, these immune system
changes do not appear to linger beyond a few days after mission completion. (Stowe 2011,
Crucian 2011).
PUBLICATION(S)
Mehta SK, Crucian BE, Stowe RP, et al. Reactivation of latent viruses is associated with
increased plasma cytokines in astronauts. Cytokine. 2012;61(1):205-209. doi:
10.1016/j.cyto.2012.09.019.
Stowe RP, Kozlova EV, Sams CF, Pierson DL, Walling DM. Latent and lytic Epstein-Barr virus gene
expression in the peripheral blood of astronauts. Journal of Medical Virology. 2011;83(6):1071-
- doi: 10.1002/jmv.22079.
Stowe RP, Sams CF, Pierson DL. Adrenocortical and immune responses following short- and
long-duration spaceflight. Aviation, Space, and Environmental Medicine. June 2011;82(6):627-
- doi: 10.3357/ASEM.2980.2011.
Crucian BE, Stowe RP, Sams CF, Pierson DL. Immune system dysregulation following short- vs
long-duration spaceflight. Aviation, Space, and Environmental Medicine. 2008;79(9):835-843.
doi: 10.3357/ASEM.2276.2008.
This investigation is ongoing and additional results are pending publication.
Electron microscopic image of 2 Epstein Barr Virus
virions (viral particles) shows round capsids—protein-
encased genetic material—loosely surrounded by the
membrane envelope. Public Library of Science image
(the original author of this photo is Liza Gross).